This invention relates to a screw cap for a bottle or like container and more particularly a screw cap comprising a plastic material.
With screw caps for bottles or like containers, which comprise a plastic material, there is the danger that, when the screw cap is screwed on to the bottle, for example and more particularly by means of an automatic bottle closure machine, the screw cap may be disposed in an angled or inclined position on the mouth of the bottle or the screwthread thereon. This may occur for example in automatic machinery if the start of the thread, being the bottom end of the screwthread in the cap, adjacent the open end of the cap, is so positioned relative to the screwthread on the bottle that it is at an angular distance of up to about 180.degree. from the start of the screwthread on the bottle. In that case, when the screwthread is initially aligned with respect to the bottle, the screwthread on the screw cap comes into contact with the screwthread on the bottle over an angle of less than 180.degree., so that the major part of the cap screwthread projects freely beyond the screwthread on the bottle, and the screw cap tilts or tips when fitted on to the bottle, the fitting operation being performed with a certain amount of pressure. When a screw cap is tilted in this manner, it will be held fast by the automatic machinery in the tilted position while it is being screwed on to the bottle, with the result that the screw cap is not properly screwed on to the neck of the bottle and does not therefore provide a satisfactory closure.